A turning point for adaptation, and the moment to take heat seriously

The headline message is unambiguous. The climate the United Kingdom plans for is not the climate the United Kingdom now has, and the gap between the two is widening. The cost of acting is materially lower than the cost of waiting. The Committee estimates that investment of around £11 billion a year, split broadly evenly between public and private sources, is what stands between us and damages projected to reach between one and five per cent of UK GDP by 2050 under a two-degree warming level.

Within this wider picture, the findings on heat warrant particular attention.

The report is clear that extreme heat is among the three most consequential climate risks facing the United Kingdom, alongside flooding and drought, and that its trajectory is steep. We must be honest about the warming pathway the country is now planning against. Two degrees of warming by 2050 is no longer a scenario to be hedged against. It is the trajectory the world is on, and global action to reduce emissions shows no sign of ramping up at the pace required to alter it.

A Well-Adapted UK makes the further point that the United Kingdom must now also prepare for a plausible four-degree world by the end of the century, and assesses risks against that high-end scenario. Under two degrees by 2050, annual heat-related excess deaths in heatwave periods could rise from the current range of 1,400 to 3,000 to between 3,800 and 10,000 each year without further adaptation. By the 2080s under a higher-warming pathway, the modelled range extends to between 10,000 and 18,000 deaths annually. These are not abstractions. They are the projected human cost of a hazard we have the tools to manage.

The summer of 2022 should be understood as a dress rehearsal of what is to come. The United Kingdom passed forty degrees for the first time in recorded history, peaking at 40.3 degrees in Lincolnshire, and the cascading failures arrived simultaneously across sectors. London Fire Brigade had its busiest day since the Second World War. Rails buckled and the East Coast main line was disconnected from King's Cross. Hospital operating theatres were rendered unusable and operations were cancelled when IT servers failed in the heat. Lifts failed in social housing tower blocks, leaving residents trapped on upper floors. Emergency services experienced a 500 per cent spike in 999 calls. Around 3,000 people died. Research published last year found that the annual chance of exceeding forty degrees somewhere in the United Kingdom has risen more than sixfold since the 1980s, with temperatures as high as 46.6 degrees now considered plausible by current models. The conditions that produced 2022 are no longer rare. They are the conditions our infrastructure, our health system and our workforce must now routinely withstand.

Even as I write, London is forecast to be warmer than Athens ahead of the bank holiday weekend, with temperatures expected to reach around 26 degrees. It is against this backdrop that the Mayor, in partnership with London Councils, has committed to developing a London Heat Risk Plan. Expected to be published in summer 2026, the Plan will set out a strategic vision for the capital's response to extreme heat, with specific actions and a financing framework. It will provide a practical model that other cities and regions could replicate, and could contribute to the development of a comparable national strategy. Other parts of the world, including the EU and China, are already looking to London's leadership on this issue with growing attention.

The built environment is central to the story. A Well-Adapted UK finds that the risk of extreme heat in homes and offices is projected to be four times higher in the 2050s than today, and that under a two-degree warming level 92 per cent of existing homes would overheat. Over half of UK homes are already at risk. In the health sector, modelled damages from heat stand at £538 million a year today in 2025 prices, and could grow by 144 per cent in the 2030s and 245 per cent by the 2050s. Heat-related hospital attendances and admissions could triple by mid-century. These pressures fall on a healthcare system already operating at its limits. The economic picture is no less serious: lower worker productivity from heat already costs up to £1.3 billion annually in lost earnings, and days of extreme overheating in schools are projected to rise sharply, with measurable consequences for examination performance and lost learning time.

Heat is not like the hazards our resilience systems were built to handle. A flood has a perimeter. A storm has a track. Heat has neither. It is an invisible transfer of energy that moves through bodies, buildings, materials and networks all at once, and it does so silently. It compounds with other hazards, with air pollution, with drought, with wildfire, multiplying the harm of each.

A Well-Adapted UK shows, too, that this burden does not fall evenly: neighbourhoods in the highest quintile of income deprivation are over seven times more likely to be in the highest quintile of vulnerability to overheating than those in the lowest. A response to heat that ignores this is a partial response.

The Committee's analysis makes equally clear that this is eminently solvable. Baroness Brown, Chair of the Adaptation Committee, puts it perfectly:

"Our lives, our landscapes and our homes are under increasing pressure from the changing climate. But we are not powerless. In an increasingly unstable world, being well adapted to climate change is fundamental to securing our food, energy and economic security.

"This report carries a message of hope. The solutions already exist, and proven technologies are available now to help the UK adapt effectively. With the right decisions and actions, we can protect the people and the places we love.

"We can protect patients and residents in overheated hospitals and care homes, children in nurseries and schools, and communities facing repeated flooding. We can support our farmers to maintain our food supplies. We can keep sports pitches usable, high streets open for business, and iconic British music festivals running safely.

"The public want to see change and the government now has an opportunity to step up and protect our way of life."

Heatwave plans deliver a benefit-cost ratio of between 10 to 1 and 30 to 1 for the 2040s. A package of adaptation across the health and social care system could reduce heat-related mortality in 2050 by close to 40 per cent. Targeted cooling in the 30 per cent most vulnerable urban areas delivers a benefit-cost ratio of around 3 to 1. Separately, modelling of residential building adaptation measures in the 30 per cent most at-risk regions across the UK suggests that they could avoid approximately 3,600 excess heat deaths annually in the 2050s. These are among the most cost-effective public health investments available to us.

This is the context in which the National Heat Risk Commission was established. The Climate Change Committee has, with this report, set the system-wide adaptation agenda for the United Kingdom. The National Heat Risk Commission exists to ensure that, for one of the most acute and rapidly escalating risks within that agenda, the gap between recommendation and delivery is closed. Heat sits across health, housing, transport, energy, water, education, labour, food and the natural environment. It demands a coordinated response that no single department, sector or tier of government can mount alone. The country does not lack analysis. It lacks delivery. The task, plainly stated, is to move from reactive recovery to proactive resilience.

The summer of 2022 showed us the country we have. A Well-Adapted UK sets out, with rigour and realism, the country we need. The work ahead is to build it.